1. Field of the Invention
This invention relates to a light emitting device.
2. Relevant Art
There are known technologies for dispersing and spreading light from a light source. For instance, Japanese Patent Laid-open Publication No. (Tokkai-Hei) 11-176220 discloses a technology which obtains the spread of light by reflecting the light and further dispersing the light two times. This technology has, however, a problem in that the amount of light is reduced because the light is reflected and the structure is apt to become complicated and large-sized.
Aside therefrom, Japanese Utility ModelLaid-open Publication No. (Jikkai-Hei) 5-15209 discloses the technology for achieving the spread of light by stacking a milky-white board and prism film. This technology has, however, a disadvantage in that the effect of scattering is insufficient, and therefore, the source of light can be seen as a dot shape in case of use of a point source of light such as LED element.
Therefore, the inventor has experimented in various ways and observed that he obtained the spread of light even in case of use of a point light source by stacking two or more scattering sheets (two sheets, for example) with striated surfaces forming plural prisms.
It is therefore an object of the present invention to provide a light emitting device capable of achieving the spread of a light source with comparatively little clustering even in the case of use of a local source of light such as a point light source or a linear light source. A light emitting device in this invention comprises a light source for supplying light, and plural light scattering devices disposed in front of the light source so as to be opposite to the direction of the light. Each of the light scattering devices comprises at least one striated surface forming plural prisms. The light is scattered by means of the prisms of the light scattering devices.
This invention enables a light emitting device to achieve the spread of light with comparatively little light clustering. In particular, the light emitted from a local source can be changed from being directional to being non-directional even in case of use of the LED""s source of light which is directional and so on (not limited to this type of light source). Therefore, the light emitting device pertaining to this invention is suitably adopted for use in the display of guardrails on the road. Moreover, in the case of using LED elements as the source of light, since LED""s have a long lifetime and low power consumption, the device can be provided using a solar battery as a power source, thereby eliminating the trouble of battery replacement. Moreover, the adoption of the LED which emits light using little power makes it easy to obtain the required power from a battery, and to eliminate defects such as broken wires caused by vehicular traffic, because conventional electric wires for supplying power are not required. Therefore, for example, the light emitting device with regard to this invention is suitable for use as an alarm light at construction sites.